CN109802325B

CN109802325B - Device for reducing fault arcs in an electrical distribution unit

Info

Publication number: CN109802325B
Application number: CN201811345714.0A
Authority: CN
Inventors: G·雷伯奇; T·加特林格
Original assignee: Eaton Intelligent Power Ltd
Current assignee: Eaton Intelligent Power Ltd
Priority date: 2017-11-17
Filing date: 2018-11-13
Publication date: 2021-01-15
Anticipated expiration: 2038-11-13
Also published as: GB2569233B; GB2569233A; GB201818547D0; DE102017127077B4; AU2018264092B2; NL2022014A; CN109802325A; DE102017127077A1; NL2022014B1; AU2018264092A1

Abstract

In a device (1) for reducing fault arcs in an electrical distribution unit, comprising a housing (2), a first busbar (3) and a second busbar (4), wherein the first busbar (3) has a first electrical connection point (5) and the second busbar (4) has a second electrical connection point (6), wherein the first busbar (3) is positioned at a distance from the second busbar (4), it is proposed that, within the housing (2), at a predetermined burn-up point (7) for a fault arc, the breakdown voltage value between the first busbar (3) and the second busbar (4) is lowest and the housing (2) is open.

Description

Device for reducing fault arcs in an electrical distribution unit

Technical Field

The present invention relates to a device for reducing fault arcing in an electrical distribution unit according to the preamble of claim 1.

Background

A fault arc occurring in a power distribution unit, such as an electrical cabinet, is a great danger due to the generation of a sudden and unpredictable high power, which may have an explosive effect. On the one hand, prolonged inactivity and expensive maintenance may occur due to damage caused by the fault arc. Furthermore, fault arcs often occur in the event of maintenance work being carried out incorrectly, so that operators are often injured.

The generation of fault arcs within power distribution units may have various causes. Often, tools or other loose objects left in a power distribution unit may cause a fault arc when the power distribution unit is turned on. Another possibility for fault arcing is that upon closing of the low voltage power switch, ionized air is expelled from the power distribution unit and reduces the breakdown voltage between the phases. Since induced voltage spikes may also occur when the low voltage power switch is turned off, a fault arc may be generated between the phases due to a combination of these two effects.

Devices are known for reducing fault arcs, which detect the occurrence of a fault arc and short-circuit the phases of the power distribution unit when a fault arc is detected, thereby removing energy from the fault arc.

Such devices, which must short-circuit the phases as quickly as possible, are very complex and expensive to manufacture. Furthermore, a quick shut-down requires the use of electronic components.

Disclosure of Invention

It is therefore an object of the present invention to provide a device for reducing fault arcs of the type described above, by means of which the disadvantages mentioned can be prevented and damage caused by the occurrence of fault arcs can be reduced, while the production is very simple.

According to the invention, this object is achieved by the features of claim 1.

The advantage is thus obtained that a predetermined position within the power distribution unit, i.e. the burn-up point in the device, can be provided for a fault arc, which can burn in a controlled environment until the power distribution unit is shut down or the fault arc self-extinguishes. This is achieved by the fact that a predetermined point with the lowest breakdown voltage is formed between the first and second busbars, at which point a fault arc may be generated in the presence of ionized gas or may be trapped in the event of generation at another location within the power distribution unit. Through the open housing, on the one hand, fault arcs, in which ionized gases can enter and/or move along the phases of the power distribution unit, can be conducted from the phases of the power distribution unit to the burn-up points within the housing. Thus, the destructive effects of a fault arc may be controlled and equipment and personnel may be protected from damage without the use of fault-prone components such as detectors.

The dependent claims relate to further advantageous embodiments of the invention.

The wording of the claims is hereby expressly referenced, whereby the claims are to be read verbatim and are hereby incorporated by reference into the specification at this point.

Drawings

The invention will now be explained in more detail with reference to the drawings, which only show a preferred embodiment by way of illustration. Specifically, the method comprises the following steps:

figure 1 shows a preferred embodiment of the device in isometric view;

figure 2 shows a preferred embodiment of the device in an exploded view; and

fig. 3 shows a part of a preferred embodiment of the device in a plan view.

Detailed Description

Fig. 1 to 3 show at least part of a preferred embodiment of a device 1 for reducing fault arcs in an electrical distribution unit, comprising a housing 2, a first busbar 3 and a second busbar 4, wherein the first busbar 3 has a first electrical connection point 5 and the second busbar 4 has a second electrical connection point 6, wherein the first busbar 3 is positioned at a distance from the second busbar 4.

The device 1 is used to reduce fault arcing within an electrical distribution unit. The reduction occurs in that uncontrolled propagation of the fault arc is prevented and the fault arc can release its energy, which has been reduced by the device, at a predetermined point. Fault arcs are unwanted arcs. The device 1 comprises a housing 2, the housing 2 preferably having an upper housing part 13 and a lower housing part 14, which are detachably fixed to each other.

The device 1 also has a first busbar 3 and a second busbar 4. In this case, the busbars 3, 4, 10 are considered to be uninsulated and solid conductors suitable for high currents, such as those used in low voltage power distribution units in busbar power distribution systems. The first busbar 3 has a first electrical connection point 5 which is provided for connection to a first phase of the power distribution unit. The second busbar 5 has a second connection point 6, which is provided for connection to a second phase of the power distribution unit.

The first busbar 3 is also positioned at a distance from the second busbar 4 such that the first busbar 3 is not in electrical contact with the second busbar 4.

Within the housing 2, at a predetermined burn-up point 7 for a fault arc, the breakdown voltage between the first busbar 3 and the second busbar 4 is lowest, and the housing 2 is opened.

Thus, the first busbar 3 and the second busbar 4 are formed in such a manner that: at a predetermined point, referred to as the burn-up point 7 for the fault arc, the breakdown voltage between the first busbar 3 and the second busbar 4 has the lowest value. The breakdown voltage is the voltage required to generate an arc. In this case, it is particularly assumed that ionized air is present to calculate the breakdown voltage. The breakdown voltage is mainly determined by the geometry of the first bus bar 3 and the second bus bar 4, in particular by the minimum distance between the first bus bar 3 and the second bus bar 4. The burnup point 7 for a fault arc can thus be embodied as a limit point in which the distance between the first busbar 3 and the second busbar 4 is minimal. Thus, the fault arc (if present) burns substantially only at the burn-up point 7 without leaving the device 1.

The fact that the breakdown voltage between the first busbar 3 and the second busbar 4 is minimal at the burn-up point 7 for the fault arc means in particular that it is at a minimum with respect to the breakdown voltage between the first busbar 3 and the second busbar 4, and in particular with respect to the breakdown voltage of the power distribution unit intended to be used, in addition to the burn-up point 7.

The fact that the housing 2 is open means that the housing 2 has an inlet 15 for unclosed gas and/or fault arcs. As a result, ionized gases which may be generated, in particular in the case of a fault disconnection process of the mains switch and/or of the fault arc, can be introduced from the outside into the housing 2 and thus also conducted to the burn-up point 7. In this case, the fault-cut process is considered to be a turn-off process of the power switch, in which an abnormally high ionized gas discharge occurs.

The advantage is thereby obtained that a predetermined point, i.e. the burn-up point 7 in the device 1, can be provided for a fault arc in the power distribution unit, wherein the fault arc can burn in a controlled environment until the power distribution unit is shut down or self-extinguishing of the fault arc occurs. This is achieved by the fact that a predetermined point with the lowest breakdown voltage is formed between the first and second busbars, at which point a fault arc may be generated in the presence of ionized gas or may be trapped in the event of generation at another location within the power distribution unit. Through the open housing 2, on the one hand, a fault arc, in which ionized gases can enter and/or move along the phases of the power distribution unit, can be conducted from the phases of the power distribution unit to the burn-up point 7 within the housing. Thus, the destructive effects of a fault arc may be controlled and equipment and personnel may be protected from damage without the use of fault-prone components such as detectors.

Preferably, it can be provided that the device 1 comprises a third busbar 10 with a third electrical connection point 11, the third busbar 10 being positioned at a distance from the first busbar 3 and the second busbar 4, the breakdown voltage between the third busbar 10 and the second busbar 4 being lowest within the housing 2 at a further predetermined burn-up point 12 for a fault arc, wherein in particular the further burn-up point 12 is formed substantially in the same way as the burn-up point 7 between the first busbar 3 and the second busbar 4. As a result, the device 1 can be applied to a power distribution unit having three phases.

The

connection points

5, 6, 11 may in particular be positioned outside the housing 2. The busbars 3, 4, 10 can then be guided from the

connection points

5, 6, 11 into the housing.

In order to form the

connection points

5, 6, 11, the busbars 3, 4, 10 can be provided with grooves at the ends, through which grooves a screw connection with the same can be provided.

The busbars 3, 4, 10 may preferably be made mainly of copper.

Further preferably, an electrical distribution unit, in particular an electrical cabinet comprising the device 1 for reducing fault arcs, is arranged within the electrical distribution unit. The power distribution unit can in particular have a phase, which is also composed of busbars. Such power distribution units are commonly used in low voltage applications in main power distribution facilities or industrial equipment.

The device may preferably be connected to the phase alone, i.e. it may have no additional ground or PEN conductors.

In particular, it is preferred that the power distribution unit has a power switch and the device 1 for reducing fault arcs is located within the power distribution unit in the region of the power switch, in particular in the unprotected path of the power switch. The power switch may in particular be an open circuit power switch and/or a low voltage power switch. In such a power switch, an arc generated during the closing process is blown out through the opening by means of air, so that ionized air is released in the region of the power switch. In this case the device 1 may be connected to the same phase of the power switch. In this case, the arrangement of the device 1 in the area of the power switch means that the device 1 is close to the power switch. In particular, the device 1 may be located in the unprotected path of the power switch.

In this case, the unprotected path of the power switch is the portion of the power distribution unit at the power switch that is under-voltage even when the power switch is closed. In particular, if the power switch blows on the downstream path and is therefore protected, this broken path is not jeopardized due to the closing process of the power switch, but the unprotected path upstream of the power switch is jeopardized. The fault arc can burn there in a controlled manner until additional protection devices also de-energize the section.

The device 1 may in particular be composed of modules. In this case, the device 1 is already provided as a finished unit and only a connection to the power distribution unit is required. The advantage of the modular device 1 is that it can be installed or replaced quickly. This is particularly advantageous because the device 1 must be replaced after a fault arc has occurred.

Alternatively, the device 1 may be installed directly in the power distribution unit.

In particular, it is advantageous if the housing 2 has a cladding portion 8 which is resistant to high temperatures and electrically insulating. The cladding portion 8 has the task of preventing damage to the housing 2 due to a fault arc for as long as possible and of insulating the interior of the housing 2 from the outside. The cladding portion 8 may also have the function of absorbing a part of the thermal energy released by the fault arc and thus cooling the fault arc. The cladding portion 8 may also in particular be composed of a plurality of portions.

The cladding portion 8 may in particular be made of ceramic or stone, preferably a refractory clay.

Preferably, the cladding portion 8 may in particular be made of a hard plastic material, preferably fibre-reinforced, such as in particular Durostone. Thus, the cladding portion 8 may additionally be better resistant to pressure waves caused by the arc.

According to a preferred embodiment of the device 1, the housing 2 has an additional outer cover 17 surrounding the refractory and electrically insulating cladding portion 8.

Alternatively, the case 2 may be constituted only by the cladding portion 8.

In particular, it is preferred that the first busbar 3 and/or the second busbar 4 have an electrode 9 at the burn-up point 7. The electrode 9 can be in particular a part of the busbar 3, 4, 10, which is made of a different material than the rest of the busbar 3, 4, 10. As a result, the parts of the busbars 3, 4, 10 that are subjected to the highest stresses due to a fault arc can be better protected against these stresses.

Preferably, the electrode 9 may be provided made of a metal or metal alloy having a melting point higher than 1,200 ℃.

It may also be preferable to provide the electrode 9 with a convex shape. Due to the convex shape, a defined and larger contact surface for a fault arc may be provided, thereby reducing wear. Also, the electric field intensity increases due to the convex shape, and as a result, the breakdown voltage can be reduced. The convex shape may in particular have a radius of substantially 50 mm.

Preferably, the electrode 9 is formed by the head of the carriage bolt 16. Therefore, the electrode 9 can be formed particularly easily.

The side opposite to the electrode 9 may preferably be formed by a counter electrode 20.

The counter electrode 20 may in particular also have a convex shape.

The minimum distance between electrode 9 and counter electrode 20 is preferably kept as small as possible in order to still comply with the required minimum leakage path and air gap requirements.

The minimum distance between the electrode 9 and the counter electrode 20 may in particular be between 10mm and 15mm, preferably substantially 11.5 mm.

Furthermore, the electrode 9 may have a conductivity lower than 10^ 7A/(Vm). Thus, the conductivity is less than copper, which is about 6X 10^ 7A/(Vm). As the conductivity decreases, the current value of the fault arc decreases, thereby reducing wear.

Particularly advantageous is the case when the electrode 9 is made of steel, in particular stainless steel. Steel, in particular stainless steel, is particularly suitable because the wear caused by a fault arc is low due to its high mechanical strength, thermal resistance and relatively low electrical conductivity.

Particularly preferably, a fault arc propagation region, which has no built-in components and extends from the connection points 5, 6 to the burn-up point 7, can be arranged between the first busbar 3 and the second busbar 4. In this case, the arc propagation region is a free space which extends from the connection points 5, 6 to the burn-up point 7, along which free space a fault arc generated outside the device 1 can propagate unhindered to the burn-up point 7. In this case, it can be provided in particular that the space between the busbars 3, 4, 10 is not enclosed by the housing 2 at the location on the housing 2 where the busbars 3, 4, 10 penetrate into the housing 2 from the outside. Thus, an unclosed inlet 15 may be formed between the busbars 3, 4, 10. Thus, a fault arc that initially propagates in the power distribution unit can be directed to the burn-up point and then retained.

Preferably, the housing 2 can be provided with a slot in the region of the connection points 5, 6, 11, through which the busbars 3, 4, 10 pass. The groove can be formed in particular between the housing upper part 13 and the housing lower part 14.

The first portions 18 of the busbars 3, 4, 10 may have a plate-like shape and in particular they may be placed in a plane, wherein preferably the second busbar 4 is located between the first busbar 3 and the third busbar 10.

The first busbar 3 and the third busbar 10 may preferably be formed substantially only by the first part 18.

The second busbar 4 may preferably have a second part 19, which second part 19 protrudes from the plane and extends over the first busbar 3 and the third busbar 10. The electrode 9 may be located on the second part 19. Thus, the burn-up points 7, 12 can be produced easily.

A reliable spacing between the busbars 3, 4, 10 can be obtained by the insulating spacer 21.

Furthermore, an electrically insulating separator with a hole may be located at the burn-up point 7 between the first busbar 3 and the second busbar 4. The separating member is not shown in fig. 1-3. The fault arc may burn in the hole, with the separator preventing lateral propagation of the fault arc, thereby limiting its capability.

Furthermore, the holes in the separator may be smaller than the electrode 9 to prevent undesired collisions between the electrode 9 and the counter electrode 20.

The holes in the separating elements can in particular have an opening edge. Thus, the fault arc can move from the outside into the hole.

Alternatively, the holes in the separate pieces may be closed, i.e. represent only holes. This hinders the fault arc from moving from the outside to the burn-up point 7. However, a fault arc can still form in the burn-up point 7, wherein the closed hole reliably holds the fault arc at the burn-up point 7.

Claims

1. A device (1) for reducing fault arcs in electrical distribution units, comprising an open housing (2), a first busbar (3) and a second busbar (4), wherein the first busbar (3) has a first electrical connection point (5) and the second busbar (4) has a second electrical connection point (6), wherein the first busbar (3) is positioned at a distance from the second busbar (4), characterized in that the first busbar (3) and the second busbar (4) are configured such that, within the housing (2), at a predetermined burn-up point (7) for a fault arc, the value of the breakdown voltage between the first busbar (3) and the second busbar (4) is lowest, wherein the burn-up point (7) is a limit point in which the distance between the first busbar (3) and the second busbar (4) is smallest, and the housing (2) has a cladding portion (8) which is resistant to high temperatures and electrically insulating, wherein the cladding portion (8) is made of ceramic or stone.

2. The device (1) for reducing fault arcs in an electrical distribution unit according to claim 1, characterized in that the first busbar (3) and/or the second busbar (4) has an electrode (9) at the burn-up point (7).

3. Device (1) for reducing fault arcs in an electrical distribution unit according to claim 2, characterized in that the electrodes (9) have a convex shape.

4. Device (1) for reducing fault arcs in electrical distribution units according to claim 2 or 3, characterized in that the electrical conductivity of the electrodes (9) is below 10^ 7A/(Vm).

5. Device (1) for reducing fault arcs in electrical distribution units according to claim 2, characterized in that the electrodes (9) are made of steel.

6. Device (1) for reducing fault arcs in an electrical distribution unit according to claim 5, characterized in that the electrodes (9) are made of stainless steel.

7. The device (1) for reducing fault arcs in an electrical distribution unit according to claim 1, characterized in that the fault arc propagation area, which has no built-in components and extends from the connection points (5, 6) to the burn-up point (7), is located between the first busbar (3) and the second busbar (4).

8. The device (1) for reducing fault arcs in an electrical distribution unit according to claim 1, characterized in that an electrically insulating separator with a hole is located at the burn-up point (7) between the first busbar (3) and the second busbar (4).

9. The device (1) for reducing fault arcs in electrical distribution units according to claim 1, characterized in that the device (1) has a third busbar (10), the third busbar (10) having a third electrical connection point (11), the third busbar (10) being located at a distance from the first busbar (3) and the second busbar (4), the breakdown voltage between the third busbar (10) and the second busbar (4) being lowest at a predetermined further burn-up point (12) for a fault arc within the housing (2), wherein the further burn-up point (12) is formed in the same way as the burn-up point (7) between the first busbar (3) and the second busbar (4).

10. A power distribution unit comprising an arrangement (1) for reducing fault arcing in a power distribution unit according to any of claims 1-9.

11. The power distribution unit according to claim 10, characterized in that the power distribution unit has a power switch and the means (1) for reducing fault arcing in the power distribution unit are located in the area of the power switch within the unprotected path of the power switch.

12. The power distribution unit of claim 10, wherein the power distribution unit is an electrical cabinet.